<!DOCTYPE html>
<html>
<head lang="en">
    <meta charset="UTF-8">
    <title></title>
    <style>
        html,
        body {
            height: 100%;
            overflow: hidden;
        }
        body {
            background: #ddd;
            background-size: cover;
            font-family: sans-serif;
            text-align: center;
        }
        .content {
            width: 400px;
            background: #fff;
            padding: 30px;
            text-align: center;
            z-index: 995;
            box-shadow: 0 3px 36px 0 rgba(0, 0, 0, 0.6);
            display: inline-block;
            margin-top: 40%;
            opacity: 0.7;
            color: #666;
            text-decoration: none;
            transition: all 0.2s;
        }
        .content:hover {
            box-shadow: 0 3px 6px 0 rgba(0, 0, 0, 0.3);
            padding: 40px;
            margin-top: 39%;
            color: #444;
        }
    </style>
</head>
<body>
<a class="content" href="javascript:history.go(0)">
    <h2>Change Background</h2> </a>

<script src='//cdnjs.cloudflare.com/ajax/libs/trianglify/0.1.5/trianglify.min.js'></script>
<script src='//cdnjs.cloudflare.com/ajax/libs/d3/3.5.5/d3.min.js'></script>
</body>
</html>


<script>
    //by @nodws
    //Click to change bg
    var rn = Math.floor((Math.random() * 150) + 60);
    var rs = Math.floor((Math.random() * 11) + 4);
    var t = new Trianglify({
        x_gradient: Trianglify.colorbrewer.Spectral[rs],
        noiseIntensity: 0,
        cellsize: rn
    });
    var pattern = t.generate(window.innerWidth, window.innerWidth + 200);
    document.body.setAttribute('style', 'background-image: ' + pattern.dataUrl);
</script>